Movable barriers, such as upward acting sectional doors, flexible rollup doors, and gates, for example, are typically characterized by operators which include various types of position sensors for use in controlling the barrier and for shutting off the operator motor when the barrier reaches a closed or open limit position, for example. Various types of position sensors have been developed, including mechanical limit switches, optical sensors and electrical devices, such as potentiometers. However, certain prior art barrier operator position sensors lack precision, are subject to mechanical or electrical errors and may require external wiring and devices which are costly to fabricate and install and increase the risk of malfunction of the operator.
Accordingly, there has been a continuing desire and need to provide barrier operators with barrier position sensors which are more reliable, versatile, accurate and less expensive than known types of sensors. It is to these ends that the present invention has been developed.